Laminate flooring usually consists of a core of a 6-12 mm fiber board, a 0.2-0.8 mm thick upper decorative surface layer of laminate and a 0.1-0.6 mm thick lower balancing layer of laminate, plastic, paper or like material. A laminate surface may consist of melamine impregnated paper. The most common core material is fiberboard with high density and good stability usually called HDF—High Density Fiberboard. Sometimes also MDF—Medium Density Fiberboard—is used as the core.
Traditional laminate floor panels of this type have been joined by means of glued tongue-and-groove joints.
In addition to such traditional floors, floor panels have been developed which do not require the use of glue and instead are joined mechanically by means of so-called mechanical locking systems. These systems comprise locking means, which lock the panels horizontally and vertically. The mechanical locking systems are usually formed by machining the core of the panel. Alternatively, parts of the locking system can be formed of a separate material, for instance aluminum or HDF, which is integrated with the floor panel, i.e., joined with the floor panel in connection with the manufacture thereof.
The main advantages of floating floors with mechanical locking systems are that they are easy to install. They can also easily be taken up again and used once more at a different location.
Definition of Some Terms
In the following text, the visible surface of the installed floor panel is called “front side”, while the opposite side of the floor panel, facing the sub floor, is called “rear side”. The edge between the front and rear side is called “joint edge”. By “horizontal plane” is meant a plane, which extends parallel to the outer part of the surface layer. Immediately juxtaposed upper parts of two adjacent joint edges of two joined floor panels together define a “vertical plane” perpendicular to the horizontal plane. By “vertical locking” is meant locking parallel to the vertical plane in D1 direction. By “horizontal locking” is meant locking parallel to the horizontal plane in D2 direction. By “first horizontal locking” is meant a horizontal locking perpendicular to the joint edges in D2 direction. By “second horizontal locking is meant a horizontal locking in the horizontal direction along the joint which prevents two panels to slide parallel to each other when they are laying in the same plane and locked both vertically and in the first horizontal direction.
By “locking systems” are meant co acting connecting elements which connect the floor panels vertically and/or horizontally in the first horizontal direction D2. By “mechanical locking system” is meant that joining can take place without glue. Mechanical locking systems can in many cases also be joined by gluing. By “integated with” means formed in one piece with the panel or factory connected to the panel.